Metallic vapor discharge device



ay 9, 1939. W NEHLS METALLIC VAPOR DISCHARGE DEVICE Filed Jan. 20, 19584 Sheets-Sheet l J', A. JM

ATTORNEY w. NEHLS 2,157,913

METALLIC VAPOR DISCHARGE DEVICE Filed Jan. 20, 1938 4 Sheets-Sheet 2 JJWATTORNEY ay 9 W39- w. NEHLs METALLIC VAPOR DISCHARGE DEVICE Filed Jan.20, 1938 4 Sheets-Sheet 3 INVENTOR VVG/Zei /Ve/ZIZS.

ATTORNEY L. 9, H939. W. NEHLS 2,157,913

METALLIC VAPOR DISCHARGE DEVICE Filed Jan. 20, 1938 4 Sheets-Sheet 4 fIZ 2f L? 5 z5 a WITNESSESZ INVENTOR MA waz/fer /Vezl ATTORNEY PatentedMay 9, 1939 UNITE STT S GFFE Walter Nehls, Berlin-Haselhorst, Germany,assignor to Siemens-Schuckertwerke Aktiengesellschaft,Berlin-Siemensstadt,

Germany, a

corporation of Germany Application January 20, 1938, Serial No. 185,913

` In Germany January 22, 1937 9 Claims.

The present invention relates to metallic vapor discharge apparatus, andmore particularly to a mercury vapor discharge apparatus.

Metallic vapor discharge apparatus have already been proposed which havemetal vessels in which cooling inserts are arranged in the dischargespace. Thus, for instance, cooling inserts have already been proposedwhich have the form of cylindrical bodies. These cooling inserts aresecured to the cover of the metallic discharge vessels and extend to apoint in the neighborhood of the cathode surface. Such cooling insertsare fed with water which has a suflicient cooling effect. However, inthe case of a water cooling the weight of the converter system isincreased on the one hand by the weight of the cooling water and on theother hand by the heavy design of the vessel and of the cooling agentconduit necessary for the reception of this weight, whereas in the caseof an air cooling diiculties arise, since the inner space to be cooledis very small and does not present sufficiently large surfaces whichmight render the air cooling effective.

According to the present invention an effective air cooling is attainedin which the above-mentioned drawbacks are removed, if a cooling insertis provided for air cooling, in which the speed of the cooling air atthe hottest points that is to say in the neighborhood of the cathode isgreatest. To: this end, it is preferable to design the cooling insert insuch a manner that its horizontal cross-section decreases towards thecathode.

The novel electric discharge apparatus presents the advantage that thewater cooling is entirely dispensed with and that the vacuum is notimpaired by the diffusion of hydrogen ions as this is the case whenemploying water cooling.

With the novel electric discharge apparatus besides the removal of theabove-mentioned drawbacks the advantage is obtained that the apparatusmay be operated Without a pump without causing in operation` animpairment of the vacuum. However, the pumpless operation and theparticular shape of the cooling inserts bring about a considerablesaving in cost and weight, which increases the efliciency of convertersystems equipped with the novel electric discharge apparatus. It may be,furthermore, added that the shape of the novel cooling inserts isparticularly advantageous. 'I'he metallic vapors rising from the cathodedo not impinge as is the case with the known inserts upon bafflingplates which deflect the metallic vapor towards the zones in which arearranged the anodes, in the (Cl. Z50-27.5)

neighborhood of which condensing metallic vapors may cause backres,short-circuits and the like. The novel electric discharge apparatus istherefore characterized by the fact that it is very reliable inoperation and has a long life.

According to the present invention the Ventilator may be directly fittedto the metallic vessel itself or preferably above the same and in such amanner that the current of cooling air separates the ventilator motorfrom the hot metal walls.

In the accompanying drawings are shown some embodiments of the inventionin diagrammatic form.

Figs. l to '7 show vertical sectional views of different types ofmercury vapor apparatus with metal vessels.

The apparatus vessel 2 cooled from below by means of a ventilator iconsists of iron and has substantially the form of a truncated cone 3 inwhose jacket are steeply inserted the anode arms which are provided withcooling ribs 5. On the cover 6 designed in the form of a doublewalledtruncated cone is arranged a second ventilator 'l communicating with theinterior of the cooling insert 8.

The upper part 9 of the cooling insert B has the shape of a cylinder andthe lower part l!) thereof that of a cone so that the part having thesmallest cross-section lies in the neighborhood of the cathode surface.In the interior of the cooling insert 8 is arranged a guide i i similarto the jacket of the cooling insert, serving to return the cooling airdrawn in by the hollow double-walled cone E. The suction inlet .l2 ofthe double-walled cone 6 is arranged in such a manner that the fresh airis drawn in from the zone of the anode bushings. The fresh air thenflows through the hollow space arranged between the outer jacket and theinner insert il to the apex I3 of the conical portion and then throughthe opening lll or the holes i5 in the interior of the part il to theventilator l. By the tapering of the cross-section of the lower portionof the cooling insert an increase in velocity of the cooling medium isattained and therefore its effectiveness is increased. In the hollowspace i@ may be arranged cooling ribs il' and i8, the number of which isgreater in the upper than in the lower portion and the cross-section ofwhich decreases in the downward direction.

In the embodiment shown in Fig. 2 the current of the cooling air flowsin the opposite direction. The cooling air is drawn in by the ventilatori9 and impinges upon the lower portion 2li of the cooling insert 2l andreturns through the hollow space 22 to the cover through whose hollowwalls 23 it reaches the outlet nozzles 24, whence it impinges directlyupon the anode bushings 25. Here the current of air issuing from thenozzle 24 unites with the rising current of air indicated by the arrow26, so that the anode bushings are intense- 1y cooled.

In the embodiment shown in Fig. 3 the current of air is drawn in fromthe rising current of air as indicated at 27 and is caused by the blower28 to impinge upon the anode bushings 30 through the nozzles 29. Also inthis `case ribs 33 welded to the outer wall of the cooling insert arearranged in the hollow space 3l oi the cooling insert 32.

In the embodiment shown in Fig. 4 fresh air is drawn in as indicated at34 after the anode bushings have been cooled thereby. The air thenissues from the upper part of the vessel as indicated at 35. In theembodiment shown in Fig. 5 are provided special suction conduits 35which draw in the fresh air from the zone of the anode bushings.

In the embodiment shown in Fig. 6 are provided various cooling insertsinstead of a single cooling insert whose lower portion has the shape ofa cone, the cooling inserts being arranged in staggered relation to oneanother in the manner that the cross-section of the cooling inserts inthe lower portion is considerably smaller than the cross-section in theupper portion of the vessel.

In the embodiments above-described the cap 37 of the cooling insert mayunder circulnstances be employed in the form of a starting or excitingelectrode. To this end, the cap must be connected to a conductor andsuitably insulated.

The cooling insert 8 shown in Fig. '7 has at its conical end opposite tothe cathode a deflccting body lili which is inserted in the tip 3i, towhich end the cooling air is supplied by the outer part IG and fromwhich the cooling air returns through the central part H. The deflectingbody 49 is so designed that the cooling air is set into a vigorouscirculation as indicated at 4S and is guided along the surface of theconical deflecting body 40 to the central portion Il. The surface of theconical deflecting body 69 may be increased by the arrangement of ribsor the like. In the tube l! separating the outer air path from the innerreturn path H perforations or slots I5 may be provided which permit aportion of the current of air supplied to the point of the cooling bodyto flow directly into the return path. These holes or slots l5 have theadvantage that a portion of the air preheated in the central part of thecooling body may be again directly dissipated so that the fresh airflows in a greater quantity to a lower point of the cooling body. Thedeecting body 40 is preferably so inserted in the point 3l' of thecooling body that it does not come into contact with the mercury vapor.However, the essential point is that it is in intimate heat contact withthe point of the cooling insert.

As will be seen from the embodiments shown it is advantageous to placethe ventilator directly on the metallic vessel, and preferably at theupper end thereof, in such a manner that the current of cooling airseparates the ventilator motor from the hot metallic walls in order toprevent the ventilator motor from being too intensely heated, whichwould shorten the life of the ventilator. In the embodiment shown theventilator is arranged at the end of the cooling insert away from thedischarge space.

As will be apparent from the embodiment shown the horizontalcross-section of the cooling insert in the neighborhood of the cathodeamounts only to a fraction of the horizontal cross-section of thecooling insert in the upper part of the condensation chamber. A coolinginsert thus shaped has the advantage that the current of the cooling airin the lower part, i. e., in the neighborhood of the cathode is renderedvery effective, since the current of the cooling air has in this casethe greatest speed owing to the shape of the lower part of the coolinginsert.

With the aid of the cooling insert shown in Fig. '7 a particularlyeffective cooling is attained directly above the cathode. In this casean intense cooling is advantageous, since heat is thereby subtracted toa great extent from the vapor rising from the cathode so that thecooling surfaces in the upper part of the vessel are not so greatlystressed. As a result of the novel arrangement according to theinvention special provisions need not be made for cooling the cathode,since the greatest portion of heat occurring in the cathode fall or inthe portion of the positive column lying in the immediate neighborhoodof the cathode is rapidly dissipated with the aid of the novel coolinginsert. The other quantities of heat are carried oi by the particularconstruction of the converter vessel, especially by the dat bottom andby the metallic arms arranged at the lower end. If a considerablereduction of the dimensions of the vessel is rendered possible by theparticular shape of the vessel, the dimensions are reduced to a furtherextent by the novel cooling insert, since also the small quantities ofheat occurring in the neighborhood of the cathode arc rapidly carriedoff by the cooling air.

What is claimed is:

1. A metal vapor arc-discharge device comprising a metallic vessel, aliquid metal cathode in the bottom of said vessel, an air cooler insertarranged in said vessel, said insert extending into proximity with saidcathode, an air duct extending into said cooling insert, said ductextending in spaced relation to said cooling insert to produce a doublepassage. means for causing air flow through said double passage, saidduct and said insert being closely spaced adjacent the end nearest thecathode to provide a restriction passage for increasing the air velocitynearest the cathode.

2. A metal vapor arc-discharge device comprising a metallic vessel, aliquid metal cathode in the bottom of said vessel, an air cooler insertarranged in said vessel, said insert extending into proximity with saidcathode, an air duct extending into said cooling insert, said ductextending in spaced relation to said cooling insert to produce a doublepassage, means for causing air fiow through said double passage, saidduct and said insert being reduced in cross section at the end adjacentthe cathode for increasing the air Velocity of said end.

3. A discharge apparatus as set forth in claim 2, characterized in thatthe cooling insert is designed in the form of a thin cone taperingtowards its lower end.

4. A vapor-electric device comprising a frustoconical containerproviding a condensing chamber, a vaporizable cathode in said chamber, acooling insert extending into said container, said insert having asubstantially cylindrical upper portion and a substantially conicallower portion tapering toward the lower end, an air guide extending intosaid cooling insert in spaced relation thereto and conforming in shapeto the cooling insert and means for circulating air through said coolinginsert and said guide.

5. A vapor-electric device comprising a frustoconical containerproviding a condensing chamber, a vaporizable cathode in said chamber, acooling insert extending into said container, said insert having asubstantially cylindrical upper portion and a substantially conicallower portion tapering toward the lower end, an air guide extending intosaid cooling insert in spaced relation thereto and conforming in shapeto the cooling insert and means for circulating air through said coolinginsert and said guide, anode arms secured to said container, anodebushings at the outer ends of Said anode `arms and means for directingthe air stream from said cooling insert around said anode bushings.

6. A vapor electric device comprising a frustoconical containerproviding a condensing chamber, a liquid metal cathode in saidcontainer, a frusto-conical top on said container, a cooling insertdepending from said top and extending into proin'mity with said cathode,that portion of the cooling insert nearest the cathode being ofsubstantially conical shape, an air guide extending into said coolinginsert, said guide conforming in shape with but spaced from the insertto provide air passages therethrough, said passages being restricted incross section adjacent the lower end of the insert, and means forpropelling air through said passages.

'7. A vapor electric device comprising a frustoconical containerproviding a condensing chamber, a liquid metal cathode in saidcontainer, a frusto-conical top on said container, a cooling insertdepending from said top and extending into proximity with said cathode,that portion of the cooling insertnearest the cathode being ofsubstantially conical shape, an air guide extending into said coolinginsert, said guide conforming in shape with but spaced from the insertto provide air passages therethrough, said passages being restricted incross section adjacent the lower end of the insert, means for propellingair through said passages, and means for increasing the heat dissipatingarea of the tip of said cooling insert.

8. A vapor electric device comprising a frustoconical containerproviding a condensing chamber, a liquid metal cathode in saidcontainer, a frusto-conical top on said container, a cooling insertdepending fromsaid top and extending into proximity with said cathode,that portion of the cooling insert nearest the cathode being ofsubstantially conical shape, an air guide extending into said coolinginsert, said guide conforming in shape with but spaced from the insertto provide air passages therethrough, said passages being restricted incross section adjacent the lower end of the insert, means for propellingair through said passages, and cooling ribs connected to said coolinginsert in the air passage.

9. A metallic vapor discharge device comprising a frusto-conicalcontainer, a vaporizable cathode in said container, a plurality of anodearms connected to said container and making an acute angle therewith, adouble walled frusto-conical top on said container having passagestherein for the passage f cooling air, anode insulators at the upperends of said anode arms, said insulators being adjacent the outerterminal of the air passages in said top, a cooling insert dependentfrom said top and extending into the vicinity of said cathode at leastthat portion of the cooling insert adjacent the cathode beingsubstantially conical, an air guide in said insert providing airpassages in said cooling insert, said passages being restricted at theend adjacent the cathode.

WALTER NEI-ILS.

